Two-stage regeneration of diesel particulate filter

ABSTRACT

In accordance with exemplary embodiments, the present invention relates to systems and methods for regeneration of a filter, particularly a diesel particulate filter. In one exemplary embodiment, a method of regeneration of a particulate matter filter is provided. The method includes providing a heat source for regeneration of a particulate matter filter. The heat source is disposed proximate or upstream from the particulate matter filter. The method also includes activating the heat source to generate a first temperature profile of the heat source, the first temperature profile including a first temperature average. The method further includes increasing the temperature of the heat source to generate a second temperature profile of the heat source, the second temperature profile including a second temperature average, wherein the second temperature average is greater than the first temperature average.

FIELD OF THE INVENTION

In accordance with exemplary embodiments, the present invention relates to systems and methods for regeneration of a filter, particularly a diesel particulate filter.

BACKGROUND

Regeneration of a diesel particulate filter (DPF) requires the addition of heat for initiating and continuing burning of accumulated particulate matter soot. As the soot burns a further increase in DPF temperature occurs. This increase in temperature is particularly prevalent during the initial regeneration process of the DPF causing a spike in the DPF temperature. Unfortunately, this temperature spike may decrease life of substrate material of the DPF. Accordingly, there is a need for a system and method for the reduction of temperature spikes in the DPFs during a regeneration process of the same.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide devices, systems and methods for regeneration of a filter. In one exemplary embodiment, a method for regeneration of a particulate matter filter is provided. The method includes providing a heat source for regeneration of the particulate matter filter. The heat source is disposed proximate or upstream from the particulate matter filter. The method also includes activating the heat source to generate a first temperature profile of the heat source, the first temperature profile including a first temperature average. The method further includes increasing the temperature of the heat source to generate a second temperature profile of the heat source, the second temperature profile including a second temperature average, wherein the second temperature average is greater than the first temperature average.

In another exemplary embodiment, a method for regeneration of a particulate matter filter is provided. The method includes providing a heat source for regeneration of a particulate matter filter, the heat source being disposed proximate or upstream from the particulate matter filter. The method also includes activating the heat source to generate a temperature profile of the particulate matter filter, the temperature profile being suitable for causing regeneration of the particulate matter filter. The method further includes adjusting the temperature of the heat source to maintain the temperature profile of the particulate matter filter within a predetermined range.

In yet another exemplary embodiment, a method for regeneration of a particulate matter filter is provided. The method includes: balancing a high exothermic reaction of a particulate matter filter by generating a first temperature profile with a heat source; and balancing a low exothermic reaction of the particulate matter filter by generating a second temperature profile with the heat source, wherein the first temperature profile of the heat source is lower than the second temperature profile of the heat source.

The above-described and other features and advantages of the exemplary embodiments will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, advantages and details of the exemplary embodiments appear, by way of example only, in the following detailed description of the exemplary embodiments, the detailed description referring to the drawings in which:

FIG. 1A illustrates a schematic view of an engine exhaust system according to an exemplary embodiment of the present invention;

FIG. 1B illustrates a schematic view of an engine exhaust system according to another exemplary embodiment of the present invention;

FIG. 2 illustrates a schematic view of an exhaust treatment system according to an exemplary embodiment of the present invention;

FIG. 3 illustrates a schematic view of another exhaust treatment system according to an exemplary embodiment of the present invention;

FIG. 4 illustrates a graph depicting a regeneration cycle of a particulate filter according to an exemplary embodiment of the present invention;

FIG. 5 illustrates a graph depicting another regeneration cycle of a particulate filter according to an exemplary embodiment of the present invention; and

FIG. 6 illustrates a graph depicting yet another regeneration cycle of a particulate filter according to an exemplary embodiment of the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention provides devices, systems and methods for prolonged service life of an exhaust treatment device, particularly diesel particulate filters (DPF), for an engine. This is achieved, at least in part, by maintaining the maximum temperature of the exhaust treatment device below specified temperatures during a regeneration process of the same. This restriction in temperature lowers thermal stresses to the exhaust treatment thereby increasing DPF durability and life.

These and other advantageous are achieved by monitoring and/or controlling the temperature input of heat sources used for regeneration of the exhaust treatment device. The monitoring and/or controlling of the temperature provided by the heat sources provide control of the temperature of the exhaust treatment device. In one particular exemplary embodiment, this temperature control is achieved through a multiple stage heating profile of the heat source, wherein an initial or first heating profile of the heat source is lower than a second and subsequent heating profile. In another exemplary embodiment, this temperature control is achieved by monitoring a temperature of the exhaust treatment device and adjusting the temperature input of the heat source to maintain the temperature of the exhaust treatment device within a desired range or below a maximum temperature. Through these and other exemplary embodiments, the initial spike in temperature of the exhaust treatment device, as previously discussed, remains within preferred ranges.

Referring to the exemplary embodiments shown in FIGS. 1A, 1B and 2, a regeneration system 10 for an exhaust treatment device (e.g., 12 of an engine exhaust system 14 is shown. The exhaust treatment device is fluidly coupled with an engine 16 through exhaust pipe 18. The regeneration system includes one or more heat sources 20 configured for increasing the temperature of the exhaust treatment device to a regeneration temperature (e.g., between about 250° C. to 750° C.). The one or more heat sources 20 are in signal and/or power communication with a control unit 22 for controlling heating provided by one or more heat sources. In one exemplary embodiment, during operation of engine 16, the control unit 22 monitors the operation of the exhaust treatment device 12 to determine when regeneration of the exhaust treatment device is necessary. Once regeneration is required, the control unit 22 causes heating of the exhaust treatment device 12 through activation of heat source 20. In one particular exemplary embodiment, the temperature of the provided heat source 20 is controlled to form one or more temperature profiles. In another particular exemplary embodiment, the temperature of the exhaust treatment device 12 is monitored and/or controlled through the use of the heat source 20 to form a temperature profile of the exhaust treatment device. In either of the particular exemplary embodiments, the initial spike in temperature of the exhaust treatment device 12 is controlled to avoid undesired effects from excessive temperatures.

Exemplary embodiments of the regeneration system 10 of the present invention are configured for providing suitable heating for various exhaust treatment devices 12. Such exhaust treatment devices may include a filtration device such as a particulate matter filter (e.g., diesel particulate filter) or otherwise. Further, exemplary embodiments of the present invention may be used in various industries utilizing stationary engines, such generators, pumps or otherwise, or industries utilizing non-stationary engines such as vehicle engines. Accordingly, it is also contemplated that the regeneration system may be used with different types of fuel burning engines, such as gasoline engines, diesel engines, hybrid engines or otherwise. In one particular exemplary embodiment, the regeneration system is utilized with a diesel particulate filter of a diesel engine.

Referring to FIGS. 1 through 3, the regeneration system 10 includes one or more heat sources 20 for providing suitable heat for regeneration of an exhaust treatment device 12. The heat source 20 provides suitable heat energy for igniting and burning filtered or captured exhaust contaminants, such as particulate matter soot or otherwise. Such heat energy includes a heat input component (i.e., BTU) and a heat temperature component (T). By example, referring to FIG. 4, the heat energy generated by the one or more heat sources 20 and applied to the exhaust treatment device 12 may include steady-state heating (i.e., constant heat input, temperature or both) or may include variable heating where the heat input, temperature or both vary over time. The heat energy forms one or more temperature profiles 40, 42 provided by the heat source 20 and a temperature profile 50 of exhaust treatment device 12. The heat energy also forms a ramp-up profile 44 where the heat source and exhaust treatment device heat up to operating (i.e., regeneration) temperature and a ramp-down profile 46 when the heat source and exhaust treatment device cools to the temperature of the surrounding environment. Also, heat energy may include one or more intermediate heat profiles 48 of the heat source and exhaust treatment device where the heat input and/or temperature changes (increases or decreases) from one temperature profile to another.

In one exemplary embodiment, the heat source 20 comprises an electrical heat source disposed proximate to the exhaust treatment device within a container. The electric heat source is in communication with the control unit 22 for initiating heating of the electric heat source. The electric heat source includes a heat element (not shown) located within an exhaust stream of the engine that is suitable to elevate temperatures of the exhaust treatment device 12 for causing regeneration of the same. In another exemplary embodiment, the heat source 20 comprises a diesel oxidation catalyst (DOC) 21 or the like configured for causing oxidation of a combustible fuel such as gas, diesel or otherwise that is injected or otherwise placed therein. The DOC 21 includes a catalyst wash coating comprising a precious metal configured for causing oxidation of the fuel. In this embodiment, fuel is injected into the exhaust stream where it undergoes oxidation or combustion within the DOC 21 to cause heating of the exhaust treatment device. The DOC 21 is typically disposed proximate to the exhaust treatment device. However, it is possible that the DOC 21 may be further disposed upstream from the exhaust treatment device 12 such as prior to a selective catalytic reduction (SCR) device 24, as shown in FIGS. 1B and 3 or otherwise. Fuel for oxidation may be injected in any suitable location. For example, referring to FIG. 1A, in one configuration a fuel injector 25 is disposed proximate to the DOC 21 such that the fuel undergoes oxidation upon entering the exhaust gas flow. In another configuration, referring to FIG. 1B, fuel is injected into an engine cylinder prior to or during expelling of exhaust gas from within the cylinder of the engine 16. The injected fuel flows down stream until it reaches the DOC 21 where oxidation of the injected fuel occurs. The exhaust gas then flow down stream where urea solution is injected, via urea injector 3 1, prior to entering an SCR device 24. The exhaust gas then flows further down stream where fuel is injected, via fuel injector 25, prior to entering DOC 21 and subsequently the particulate matter filter 13. With respect to injected fuels, the heat input and temperature of the heat source can be controlled by controlling the flow rate of fuel into the DOC 21. The DOC 21, urea injector 31 and fuel injector 25 are controlled through control unit 22. Other configurations are possible.

The regeneration system further contemplates one or more sensors for determining and/or monitoring the temperature of exhaust gas flowing into and out of the heat source 20, exhaust treatment device 12 or both. Such sensors are particularly advantageous for monitoring the operation (e.g., efficiency or otherwise) of the heat source 20, monitoring the temperature of the exhaust treatment device 12 during regeneration or otherwise. Further, with real-time monitoring of the temperature, it is possible to control the heat input of the heat source 20 for further controlling the temperature of the exhaust treatment device 12 during regeneration.

For example, referring to the exemplary embodiment shown in FIGS. 1A, 1B and 2, the regeneration system 10 includes a first temperature sensor 26 disposed proximate to an inlet of the heat source 20 for monitoring the temperature of exhaust gas entering the heat source 20. The embodiment also includes a second temperature sensor 27 disposed proximate to an outlet to the heat source for monitoring the temperature of exhaust gas exiting the heat source 20. By knowing these temperatures, and in certain configurations other information related to injection of fuel or current to the electric heater, it is possible to determine the heat input from the heat source 20 to the exhaust treatment device 12. In another exemplary embodiment, referring to FIG. 3, the regeneration system further includes a third temperature sensor 28 disposed proximate to an exit of the exhaust treatment device 12 for measuring the temperature of the exhaust gas exiting the same. The temperature sensed by the third sensor 28 provides an indication of the operation temperature of the exhaust treatment device 12. It should be appreciated that the temperature sensors may comprise any suitable high temperature sensor, such as thermocouples or other temperature sensors used for monitoring temperatures of exhaust components of an engine.

The heat sources 20 are configured to provide suitable patterns or profiles of heat input and temperature for the exhaust treatment device 12. For example, in one configuration the heat source 20 provides constant or steady-state heat input or temperature for the exhaust treatment device 12. In this configuration the heat input and temperature generated by the heat source 20 remains relatively constant. In another configuration the heat source 20 provides variable heat input or temperature into the exhaust treatment device 12. In this configuration, the heat generates an average temperature over the duration of the heating or heat profile. Also, the constant or steady-state heat input may also include an average temperature, which generally is the temperature of the constant or steady-state heat input.

In one particularly advantageous embodiment, the regeneration system 10 includes one or more heat input or temperature profiles forming an increase in the temperature delivery or output of the heat source 20. This stepped or increasing temperature profile is particularly advantageous for maintaining optimum operating ranges of the exhaust treatment device 12. This is because, as previously mentioned, the temperature of the exhaust treatment device 12 can dramatically increase during initial regeneration of the device. Through this increasing profile, once the burn rate of particulate matter soot begins to decrease, the temperature delivered to the heat source 20 can be increased for maintaining temperatures of the exhaust treatment device 12 within desired operating or regeneration temperature ranges ensuring complete regeneration of the device.

In a first configuration of an increasing temperature profile, the temperature of the heat source 20 is varied, over time, from a first set point or average temperature to a second set point or average temperature, wherein the second set point or average temperature is greater than the first set point or average temperature. In another example, a temperature profile is provided including a varying temperature, wherein the initial or first temperature or temperature average is lower than a subsequent or second temperature or temperature average. As should be appreciated, both of these particular examples include an initial or first temperature that is lower than a subsequent second temperature for reducing potential or maximum temperature spike of the exhaust treatment device 12 during initial burn off of the particulate matter during regeneration.

In a second configuration of an increasing temperature profile, the temperature of the exhaust treatment device 12 is maintained between a temperature minimum and a temperature maximum. This is achieved by controlling the heat input and/or temperature of the of the heat source 20. As previously mentioned, the maintaining of the temperature of the exhaust treatment device 12 within a range may be achieved through known temperature settings of the heat sources 20. Alternatively, or in addition to known temperatures, the regeneration system may also include one or more temperature sensors, as previously discussed, for monitoring the temperature of the exhaust treatment device, heat source or both. As such, the heat input and temperature of the heat source can be modified to maintain the temperature of the exhaust treatment device 12 between minimum and maximum temperatures or in a specific temperature range for regeneration.

The minimum temperature for regeneration of an exhaust treatment device varies greatly depending on many factors, such as the minimum temperature required for regeneration and the maximum temperature rating of the exhaust treatment device 12. In one configuration it is contemplated that the minimum temperature comprises about 250° C., 350° C. or more. With respect to a maximum temperature, it is contemplated that the maximum temperature of the exhaust treatment device and/or heat source comprises about 750° C. Accordingly, it is further contemplated that the regeneration system is configured to maintain the exhaust treatment device 12 within a regenerative operating range. For example, it is contemplated that during regeneration the temperature of the exhaust treatment device 12 and/or heat source 20 output temp is in the temperature range of about 250° C. to 750° C. Further, in one particular exemplary embodiment, the regeneration system 10 maintains the temperature of the exhaust treatment device 12 within a desired temperature range. Such range may comprise a 200° C. range, 100° C. range, 50° C. range, 25° C. range or less. For example, should a preferred regenerative temperature comprise 600° C. and a preferred operating range comprise 100° C. then in one configuration the regeneration system maintains the temperature of the exhaust treatment device 12 between about 550° C. to about 650° C. It should be appreciated that other configurations, e.g., minimum temperature, maximum temperature and temperature ranges may exist depending on the characteristics and heat resistance of the exhaust treatment device.

The duration time of the temperature profile(s) of the heat source 20 and/or exhaust treatment device 12 are suitable for causing substantially complete regeneration of the exhaust treatment device 12. In one configuration the temperature profile includes a predetermined time duration. For example, with respect to temperature profiles of the heat source, each profile or profiles may include a predetermined time duration calculated to cause substantially complete regeneration of the exhaust treatment device 12 given the heat input and temperatures of the heat source 20. In another configuration the time duration is based upon factors such as temperature of the exhaust treatment device 12 and/or heat source 20 output, efficiency of the heat source, amount particulate matter soot or otherwise. In this example, with respect to temperature profiles of the exhaust treatment device 12, the time duration of the heat profile may be based upon sensed or expected temperatures of the exhaust treatment device 12.

The control unit 22 of the regeneration system is configured for controlling application or delivery of heat to the exhaust treatment device 12. Accordingly, the control unit 22 may be in communication with the exhaust treatment device 12, heat sources 20, temperature sensor 26, 28, 29, injector 25 or other component of the regeneration system 10. The control unit includes suitable software and algorithms for controlling regeneration of the exhaust treatment device 12 and more particularly maintaining the temperature of the exhaust treatment device 12 within acceptable levels or ranges. The control unit 22 may comprise a stand alone unit configured for controlling only the components of the regeneration system 10, which may be in communication with one or more other control units. Alternatively, the control unit comprises a portion of a more encompassing control unit configured to control multiple systems, such as an engine control unit. The control unit may be configured to be calibrated to compensate for different configurations of heat sources, temperature sensors, exhaust treatment device or otherwise. Also, this calibration may take into account the location of the heat sources and temperature sensors with respect to the exhaust treatment device. Other calibration configurations of the control unit are possible.

In view of the foregoing, referring to FIG. 4, a first graph depicting two regeneration cycles of a regeneration system 10 of the present invention are shown. The graph includes a first regeneration cycle having an uncontrolled single stage temperature profile and a second regeneration cycle having a two stage temperature profile. The graph depicts the temperature profile of the heat sources 20 and a particulate matter filter 13 over time. With reference to the first regeneration cycle, the cycle includes a single heat source temperature profile 30 having a ramp-up temperature profile 32 and a ramp-down temperature profile 34. Corresponding to the first temperature profile of the heat source 20, a particulate matter filter temperature profile 36 is generated. As shown, during initial regeneration of the particulate matter filter 13 the temperature of the filter spikes above an undesirable temperature level 38 for this configuration. After the initial soot is burned off of the particulate matter filter 13, the filter returns to a temperature roughly corresponding to the temperature provided by the heat source 20. With reference to the second regeneration cycle, the cycle includes a first heat source temperature profile 40 and a second heat source temperature profile 42. The cycle also includes ramp-up temperature profile 44, ramp-down temperature profile 46 and intermediate temperature profile 48. As shown, during initial regeneration of the particulate matter filter 13 the temperature of the filter increases; however, the maximum level of the increase is reduced and below undesirable temperature level 38 due to a lower initial temperature of the first heat source temperature profile 40. As the temperature of the particulate matter filter 13 decreases the temperature output of the heat source 20 increases as exemplified in intermediate temperature profile 48 until reaching the second heat source temperature profile 42 wherein the temperature of the filter 12 generally corresponds to the temperature of the second heat source temperature profile.

Referring to FIGS. 1A and 5, a second graph depicting a regeneration cycle of a regeneration system 10 of the present invention is shown. The graph includes a temperature profile 52 of an operation cycle of a particulate matter filter 13. The operation cycle includes a ramp-up temperature profile 54 and ramp-down temperature profile 56. As shown, the desired temperature profile is generally steady-state or constant during the regeneration cycle and is within a desired operation range, which is below undesirable temperature level 38. The temperature profile of the exhaust treatment device is controlled through the heat source 20, as depicted by heat source temperature profile 58. In this configuration, the heat source 20 provides heat input and temperature to the exhaust treatment device 12 for raising the temperature of the exhaust treatment device to a desire regenerative operating range. Once the exhaust treatment device 12 reaches this range, as indicated by temperature sensor 28, the heat source 20 decreases heat input and/or temperature to account for the initial soot burn of the exhaust treatment device. Once the initial burn dissipates the heat source 20 again raises heat input and/or temperature to maintain the generally steady-state constant temperature of the exhaust treatment device 12.

Referring to FIGS. 1A and 6, a third graph depicting a regeneration cycle of a regeneration system 10 of the present invention is shown. The graph includes a plurality of multiple heat source temperature profiles 60, each being generally constant. The heat source profiles includes a ramp-up temperature profile 62, ramp-down temperature profile 64 and a plurality or multiple intermediate temperature profiles 66. The plurality of heat source temperature profiles 60 creates a particulate matter filter temperature profile 68. Similar to the graph shown in FIG. 4, the particulate matter filter profile 68 is created by the temperature profile of the heat source 20 and the heat of burning particulates. The initial or first temperature profile of the heat source 20 is at a lower level than a subsequent temperature profile level and remains at that level until the initial soot burn off of the particulate matter filter 13 begins to dissipate. The temperature profiles of the heat source 20 increase and/or decreases to form a desired temperature profile 68 of the particulate matter filter 13. Such changes in the temperature profile of the heat source may additionally be based upon optimum regeneration temperature, efficiency of the regeneration system or otherwise.

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. A method for regeneration of a particulate matter filter, comprising: providing a heat source for regeneration of a particulate matter filter, the heat source being disposed upstream from the particulate matter filter; activating the heat source to generate a first temperature profile of the heat source, the first temperature profile including a first temperature average; and increasing the temperature of the heat source to generate a second temperature profile of the heat source, the second temperature profile including a second temperature average, wherein the second temperature average is greater than the first temperature average.
 2. The method of claim 1, wherein the first temperature profile includes a generally constant temperature, the second temperature profile includes a generally constant temperature or both the first and second temperature profiles include generally constant temperatures.
 3. The method of claim 1, wherein the first temperature profile includes a varying temperature, the second temperature profile includes a varying temperature or both the first and the second temperature profiles are varying in temperature.
 4. The method of claim 1, wherein the heat source comprises an electric heater disposed proximate to the particulate matter filter.
 5. The method of claim 1, wherein the heat source comprises oxidation of fuel within a diesel oxidation catalyst disposed upstream from the particulate matter filter.
 6. The method of claim 1, wherein more than two temperature profiles are generated with the heat source.
 7. The method of claim 1, wherein a temperature of an exhaust gas is measured upstream from the heat source with a first temperature sensor, and wherein the temperature of the exhaust gas is measured downstream from the heat source with a second temperature sensor.
 8. The method of claim 7, wherein a control unit is provided for causing generation of the first temperature profile and the second temperature profile.
 9. The method of claim 8, wherein the control unit is in communication with the first and second temperature sensor, and wherein the first and second temperature profiles are based upon measurements taken from the first and second temperature sensor.
 10. The method of claim 9, wherein the control unit is in further communication with a third temperature sensor located downstream from the exhaust treatment device, and wherein the first and second temperature profiles are further based upon measurements from the first temperature sensor, third temperature sensor or both.
 11. A method for regeneration of a particulate matter filter, comprising: providing a heat source for regeneration of a particulate matter filter, the heat source being disposed upstream from the particulate matter filter; activating the heat source to generate a temperature profile of the particulate matter filter, the temperature profile being suitable for causing regeneration of the particulate matter filter; and adjusting the temperature of the heat source to maintain the temperature profile of the particulate matter filter within a predetermined range during regeneration of the particulate matter filter.
 12. The method of claim 11, wherein a temperature of an exhaust gas is measured downstream from the particulate matter filter with a temperature sensor.
 13. The method of claim 12, wherein a control unit is provided for activating the heat source to form the temperature profile of the particulate matter filter.
 14. The method of claim 13, wherein the control unit is in communication with the temperature sensor, and wherein the temperature profiles are based upon measurements from the temperature sensor.
 15. The method of claim 11, wherein the heat source comprises an electric heater disposed proximate to the particulate matter filter.
 16. The method of claim 11, wherein the heat source comprises oxidation of fuel within a diesel oxidation catalyst disposed upstream from the particulate matter filter.
 17. A method for regeneration of a particulate matter filter, comprising: balancing a high exothermic reaction of a particulate matter filter by generating a first temperature profile with a heat source; and balancing a low exothermic reaction of the particulate matter filter by generating a second temperature profile with the heat source, wherein the first temperature profile of the heat source is lower than the second temperature profile of the heat source.
 18. The method of claim 17, wherein balancing of the high and low exothermic reaction is performed by a controller.
 19. The method of claim 18, wherein the controller is in signal communication with a temperature sensor located downstream from the particulate matter sensor.
 20. The method of claim 17, wherein the first temperature profile and the second temperature profile each include a generally constant temperature. 